[PATCH] drm/amd/amdgpu: fix missing lock for cper.ring->rptr/wptr access

[Zhou1, Tao]

[AMD Official Use Only - AMD Internal Distribution Only]

Reviewed-by: Tao Zhou <tao.zhou1 at amd.com>

> -----Original Message-----
> From: Wang, Yang(Kevin) <KevinYang.Wang at amd.com>
> Sent: Thursday, July 24, 2025 3:39 PM
> To: amd-gfx at lists.freedesktop.org
> Cc: Zhang, Hawking <Hawking.Zhang at amd.com>; Zhou1, Tao
> <Tao.Zhou1 at amd.com>
> Subject: [PATCH] drm/amd/amdgpu: fix missing lock for cper.ring->rptr/wptr access
>
> Add lock protection for 'ring->wptr'/'ring->rptr' to ensure the correct execution.
>
> Fixes: 8652920d2c00 ("drm/amdgpu: add mutex lock for cper ring")
> Signed-off-by: Yang Wang <kevinyang.wang at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_cper.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cper.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_cper.c
> index 15dde1f50328..25252231a68a 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cper.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cper.c
> @@ -459,7 +459,7 @@ static u32 amdgpu_cper_ring_get_ent_sz(struct
> amdgpu_ring *ring, u64 pos)
>
>  void amdgpu_cper_ring_write(struct amdgpu_ring *ring, void *src, int count)  {
> -     u64 pos, wptr_old, rptr = *ring->rptr_cpu_addr & ring->ptr_mask;
> +     u64 pos, wptr_old, rptr;
>       int rec_cnt_dw = count >> 2;
>       u32 chunk, ent_sz;
>       u8 *s = (u8 *)src;
> @@ -472,9 +472,11 @@ void amdgpu_cper_ring_write(struct amdgpu_ring *ring,
> void *src, int count)
>               return;
>       }
>
> +     mutex_lock(&ring->adev->cper.ring_lock);
> +
>       wptr_old = ring->wptr;
> +     rptr = *ring->rptr_cpu_addr & ring->ptr_mask;
>
> -     mutex_lock(&ring->adev->cper.ring_lock);
>       while (count) {
>               ent_sz = amdgpu_cper_ring_get_ent_sz(ring, ring->wptr);
>               chunk = umin(ent_sz, count);
> --
> 2.34.1